A “security document” such as an electronic passport (ePassport) or an electronic identification (eID) card may comprise an “inlay substrate” (or “inlay laminate”) which is typically a sheet (or layer) of material such as Teslin™, with a Radio Frequency Identification (RFID) chip module and corresponding antenna mounted therein. An ePassport may have an additional “cover layer” (or “cover material”), such as PVC-coated paper, cloth or synthetic leather laminated (or joined) thereto. An eID card may have an additional upper “overlay layer” of anti-scratch, typically transparent material, with an adhesive backing laminated thereto, and an additional “bottom layer”, which may have a magnetic stripe.
In the main hereinafter, the inlay substrate (or inlay laminate) portion of security documents which are electronic passports (ePassport) are discussed. The inlay substrate, with transponder module and antenna incorporated therein may be referred to as a “secure inlay”.
Examples of Some Secure Documents
An electronic passport cover (or “e-cover”) generally comprises a hinged cover comprising a front panel (or portion) and a back panel (or portion), and an insert of several pages disposed within the e-cover. The “passport card” is an alternative to an ordinary US passport cover. Both the passport cover and passport card include a vicinity-read radio frequency identification (RFID) chip. The RFID chip in the passport card (eID card) is designed to be readable at a greater distance than that of the passport cover, and to prevent the RFID chip from being read when the passport card (eID card) is not being used, the passport card (eID card) typically comes with a sleeve designed to block the RFID chip from being read while the card is in the sleeve. See, for example, US Published Application No. 2007/0205953, incorporated by reference herein.
FIG. 1A shows an example of a security document which may an electronic “passport cover” (e-cover) comprising an inlay substrate (layer) and a cover layer (cover material). An RFID chip module (not shown) and corresponding antenna (not shown) may be mounted (disposed, embedded) in the inlay substrate. An insert having several pages (not shown) for presenting printed information and receiving visa (entry and exit) stamps may be mounted within the passport cover. Notice that the passport cover, cover layer and inlay substrate may be folded, resulting in a front cover panel (portion) and a back cover panel (portion) of the passport cover. The passport cover is shown partially open (partially closed). In use, when being examined, scanned or stamped by a border (Vama, Duoanes) official, the passport cover may be fully open. When the passport cover is closed, the cover layer is external to (surrounds) the inlay substrate. The passport cover, cover layer and inlay substrate are not shown to scale.
FIG. 1B shows an example of a security document which may be an identification (eID) card having an inlay substrate (layer), and additional layers comprising a top overlay layer and a bottom layer. An RFID chip module and corresponding antenna (not shown) may be mounted in the inlay substrate (middle layer). The additional top and bottom layers may be anti-scratch layers, and protect the inlay substrate in the middle from top and bottom. The eID card, inlay substrate layer and top and bottom layers are not shown to scale.
Examples of Some RFID Chip Modules
In the main hereinafter, the discussion may focus on RFID chip modules which are leadframe-type modules. However, some of the techniques for producing security documents discussed herein may also be applicable to epoxy glass modules (chip on FR4, wire bonded, glob topped).
FIG. 1C shows an example of an RFID chip module which is a “leadframe module” comprising:                a leadframe having a thickness of approximately 80 μm        an RFID chip disposed on and connected by wire bonds to the leadframe, having a thickness of approximately 80 μm        a mold mass disposed over the chip and wire bonds, having a thickness of approximately 240 μm        an antenna wire having end portions connected to “connection areas” of the leadframe, typically on a side of the leadframe opposite the RFID chip (as shown), but the end portions can also be connected to connection areas on the same side of the lead frame as the RFID chip.        
The total thickness of the leadframe module may be 320 μm, such as for an inlay substrate having a thickness of approximately 356 μm. Generally, the chip module will be disposed in a recess in the inlay substrate so as to be concealed therein.
FIG. 1D shows an example of an RFID chip module which is an “epoxy glass module” comprising:                an interconnect substrate, such as FR4 (printed circuit board substrate material), having a thickness of approximately 100 μm (FR4 is 100 μm and the chip & glob top 160 μm=overall 260 μm)        an RFID chip, wire-bonded (alternatively flip-chip connected with solder bumps and underfiller, as illustrated) to the FR4 substrate, having a thickness of approximately 100        a glob top epoxy disposed over the chip and connections, having a thickness with chip of approximately 160 μm        an antenna wire having ends connected to “connection pads”, typically on the same side of the FR4 substrate as the RFID chip, but can also be connected on the opposite side of the FR4 substrate as the chip.        
The total thickness of the epoxy glass module may be 260 μm, such as for an inlay substrate having a thickness of approximately 365 μm. Generally, the chip module will be disposed in a recess in the inlay substrate so as to be concealed therein.
Generally speaking, epoxy glass modules are inherently somewhat more flexible than leadframe modules. This is a factor that may need to be taken into consideration when incorporating an RFID module into a secure document. And, whereas leadframe modules are typically rectangular, the mold part (glob top) of an epoxy glass module are typically round.
It should be understood that, although FIG. 1D shows a flip chip connection between the RFID chip and the FR4 substrate, the chip can be wire-bonded to the substrate (such as was shown in FIG. 1C, for the leadframe-type module.)